Fully automatic systems which comprise combinations of hydraulic torque converter transmissions and complementary gears are well known in the art and common on the market. Although many of these systems have hydromechanical control systems, the increased demands for a system which is capable of varying the shift conditions in relation to a wide variety of factors, as well as the increased demand for inclusion of safety functions in the basic automatic systems, has resulted in the development of electronic contol systems for this purpose. An example of a system incorporating such electronic controls is that disclosed in commonly assigned U.S. Pat. No. 4,033,202.
While these systems, and similar systems, make it possible to tailor the operation to most conventional demands, such systems become large and quite complicated as the demands thereon increase. Further, such systems do not permit variations in the basic operating mode without a complete redesign and reconstruction of the system. Thus, the electronic autopilots or control systems of the type in question are not able to serve transmission units and assemblies which are of various forms and types, and which incorporate various accessories. Further, due to the complexity involved, such systems are normally limited to determining the drive connections in dependence upon primary speeds, secondary speeds and speed ratios only.